Correlation vs. Causation Regression Correlation vs. Causation

A ____________ is often used to present bivariate _____________ data A ____________ is often used to present bivariate _____________ data. Each variable is represented on an axis and the axes are labeled accordingly. A scatter plot displays data as points on a grid using the associated numbers as coordinates or ordered pairs _______. The way the points are arranged by themselves in a scatter plot may or may not suggest a relationship between the two variables. For instance, by reading the graph below, do you think there is a relationship between the hours spent studying and exam grades? Scatter Plot Quantitative ( X, Y)

Correlation A statistical way to measure the relationship between two sets of data. Means that both things are observed at the same time.

Measuring Correlation Correlation is measured by the correlation coefficient, R. R is a number between -1 and 1. There are 2 traits to correlation: Direction Strength

Positive Correlation (+) Negative Correlation (-) Direction

Strength Weak ---------------------------> Strong R value (correlation coefficient) 0 ---------------------------> 1 Strength

Put the correlation coefficients in order from weakest to strongest Ex 1: 0.87, -0.81, 0.43, 0.07, -0.98 Ex 2: 0.32, -0.65, 0.63, -0.42, 0.04 0.07, 0.43, -0.81, 0.87, & -0.98 0.04, 0.32, -0.42, 0.63, & -0.65

Match the Correlation Coefficient to the graph Correlation Coefficients -1 -0.5 0 0.5 1

Match the Correlation Coefficient to the graph Correlation Coefficients -1 -0.5 0 0.5 1

Match the Correlation Coefficient to the graph Correlation Coefficients -1 -0.5 0 0.5 1

Match the Correlation Coefficient to the graph Correlation Coefficients -1 -0.5 0 0.5 1

Match the Correlation Coefficient to the graph Correlation Coefficients -1 -0.5 0 0.5 1

Positive, Negative, or No Correlation? The number of hours you work vs. The amount of money in your bank account Positive B. The number of hours workers receive safety training vs. The number of accidents on the job. Negative Draw a sketch of a graph to discuss…. C. The number of students at Rockdale vs. The number of dogs in Atlanta No Correlation

Positive, Negative, or No Correlation? D. The number of heaters sold vs. The months in order from February to July Negative E. The number of rice dishes eaten vs. The number of cars on I-75 throughout the day No Correlation F. The number of calories burned/lost vs. The amount of hours walked Positive

Correlation Causation Means that both things are observed at the same time. Means that one thing will cause the other.

You can have correlation without causation There is a correlation (relationship) between the number of firemen fighting a fire and the size of the fire. (The more firefighters at the scene means that there is a bigger fire.) However, this doesn’t mean that bringing more firemen will cause the size of the fire to increase Correlation does not imply Causation

Is it Causation or Correlation? Ex 1. A recent study showed that college students were more likely to vote than their peers who were not in school. Correlation Ex 2. Dr. Shaw noticed that there was more trash in the hallways after 2nd period than 1st period. Correlation First two examples: correlations Last example: causation Ex 3. You hit your little sister and she cries Causation